Multiple network allocation vector operation

ABSTRACT

A wireless device determines a Basic Service Set (BSS) associated with a wireless transmitter by receiving a first frame, determining an address of the first frame, receiving a second frame, and determining, using the address of the first frame, a property of the second frame. Determining the property of the second frame may include determining whether the second frame is intra-BSS frame or an inter-BSS frame. Determining the property of the second frame may be performed by comparing an address of the second frame with the address of the first frame, and the second frame determined to be an intra-BSS frame when the address of the first frame matches the address of the second frame, and determined to be an inter-BSS frame otherwise. The address of the first frame may be a transmit address (TA).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/267,214 filed Dec. 14, 2015, and U.S. ProvisionalPatent Application No. 62/404,608 filed Oct. 5, 2016, which areincorporated by reference herein in their entireties.

BACKGROUND 1. Technical Field

The technology described herein relates generally to wirelessnetworking. More particularly, the technology relates to thecommunication of management of Network Allocation Vectors (NAVs) used invirtual carrier sensing in a wireless network.

2. Description of the Related Art

Wireless LAN (WLAN) devices are currently being deployed in diverseenvironments. Some of these environments have large numbers of accesspoints (APs) and non-AP stations in geographically limited areas. Inaddition, WLAN devices are increasingly required to support a variety ofapplications such as video, cloud access, and offloading. In particular,video traffic is expected to be the dominant type of traffic in manyhigh efficiency WLAN deployments. With the real-time requirements ofsome of these applications, WLAN users demand improved performance indelivering their applications, including improved power consumption forbattery-operated devices.

A WLAN is being standardized by the IEEE (Institute of Electrical andElectronics Engineers) Part 11 under the name of “Wireless LAN MediumAccess Control (MAC) and physical Layer (PHY) Specifications.” A seriesof standards have been adopted as the WLAN evolved, including IEEE Std802.11™-2012 (March 2012) (IEEE 802.11n). The IEEE Std 802.11 wassubsequently amended by IEEE Std 802.11ae™-2012, IEEE Std802.11aa™-2012, IEEE Std 802.11ad™-2012, and IEEE Std 802.11ac™-2013(IEEE 802.11ac).

Recently, an amendment focused on providing a High Efficiency (HE) WLANin high-density scenarios is being developed by the IEEE 802.11ax taskgroup. The 802.11ax amendment focuses on improving metrics that reflectuser experience, such as average per station throughput, the 5thpercentile of per station throughput of a group of stations, and areathroughput. Improvements may be made to support environments such aswireless corporate offices, outdoor hotspots, dense residentialapartments, and stadiums.

Wireless networks may employ virtual carrier sensing using NetworkAllocation Vectors (NAVs). A station's NAV, when set, indicates that insome circumstances the station should not attempt to transmit, even ifthe wireless medium the transmission would be on appears to not be inuse.

In a HE WLAN system, a station may maintain two NAV values. A first NAVvalue relates to Intra-Basic Service Set (Intra-BSS) frames (framestransmitted by devices associated with a same AP as the station) and asecond NAV value that relates to Inter-BSS frames (frames transmitted bydevices that are not associated with the same AP as the station) andframes that cannot be determined to be Intra-BSS frames or Inter-BSSframes.

When a frame cannot be identified as either an Intra-BSS frame or anInter-BSS frame, operations relying on the first NAV, the second NAV, orboth may prevent uses of the wireless medium that would be allowed ifthe frame was properly identified, and thereby reduce the efficiency ofthe HE WLAN system.

SUMMARY

In an embodiment, a method performed by a first wireless device fordetermining a Basic Service Set (BSS) associated with a wirelesstransmitter comprises receiving, by the first wireless device, a firstframe, determining an address of the first frame, receiving, by thefirst wireless device, a second frame, and determining, using theaddress of the first frame, a property of the second frame.

In an embodiment, determining the property of the second frame comprisesdetermining whether the second frame is intra-BSS frame or an inter-BSSframe.

In an embodiment, determining the property of the second frame comprisescomparing an address of the second frame with the address of the firstframe. The second frame is determined to be an intra-BSS frame when theaddress of the first frame matches the address of the second frame, anddetermined to be an inter-BSS frame when the address of the first framefails to match with the address of the second frame.

In an embodiment, the address of the second frame is a receive address(RA) and the address of the first frame is a transmit address (TA).

In an embodiment, the method further comprises setting an inter-BSSnetwork allocation vector (NAV) in response to determining that thesecond frame is an inter-BSS frame, and setting an intra-BSS NAV inresponse to determining that the second frame is an intra-BSS frame.

In an embodiment, the first frame is not targeted to the first wirelessdevice.

In an embodiment, the second frame is not targeted to the first wirelessdevice.

In an embodiment, the method further comprises determining whether thefirst frame is an intra-BSS frame, and determining the address of thefirst frame comprises storing the address of the first frame when thefirst frame is determined to be an intra-BSS frame.

In an embodiment, the address of the first frame is a transmitteraddress of a second wireless device transmitting the first frame.

In an embodiment, the address of the first frame is an address of aholder of a Transmission Opportunity (TXOP) in which the first frame istransmitted.

In an embodiment, receiving the second frame comprises receiving thesecond frame within a Short Intra-Frame Space (SIFS) of an end ofreceiving the first frame.

In an embodiment, receiving the second frame comprises receiving thesecond frame within a duration of a Transmission Opportunity (TXOP).

In an embodiment, the method further comprises determining whether thesecond frame includes valid BSS information. The BSS informationprovides an indication of a BSS that the device transmitting the firstframe is associated with. Determining, using the address of the firstframe, the property of the second frame is performed in response to thesecond frame being determined to not include the valid BSS information.

In an embodiment, the first frame is a request-to-send (RTS) frame andthe second frame is a clear-to-send (CTS) frame, or the first frame is adata frame and the second frame is an acknowledgement frame.

In an embodiment, a wireless device comprises a receiver circuit. Thewireless device is to determine a Basic Service Set (BSS) associatedwith a wireless transmitter. Determining the BSS associated with thewireless transmitter comprises receiving, using the receiver circuit,first frame, determining an address of the first frame, receiving, usingthe receiver circuit, a second frame, and determining, using the addressof the first frame, a property of the second frame.

In an embodiment, determining the property of the second frame comprisesdetermining whether the second frame is intra-BSS frame or an inter-BSSframe.

In an embodiment, determining the property of the second frame comprisescomparing an address of the second frame with the address of the firstframe. The second frame is determined to be an intra-BSS frame when theaddress of the first frame matches the address of the second frame. Thesecond frame is determined to be an inter-BSS frame when the address ofthe first frame fails to match with the address of the second frame.

In an embodiment, the address of the second frame is a receive address(RA) and the address of the first frame is a transmit address (TA).

In an embodiment, the first frame is not targeted to the first wirelessdevice and the second frame is not targeted to the first wirelessdevice.

In an embodiment, determining the BSS associated with the wirelesstransmitter comprises determining whether the first frame is anintra-BSS frame, and determining the address of the first framecomprises storing the address of the first frame when the first frame isdetermined to be an intra-BSS frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates wireless networks, according to an embodiment.

FIG. 2 is a schematic diagram of a wireless device, according to anembodiment.

FIG. 3A illustrates components of a wireless device configured totransmit data, according to an embodiment.

FIG. 3B illustrates components of a wireless device configured toreceive data, according to an embodiment.

FIG. 4 illustrates Inter-Frame Space (IFS) relationships.

FIG. 5 illustrates a Carrier Sense Multiple Access/Collision Avoidance(CSMA/CA) based frame transmission procedure.

FIG. 6A illustrates an HE PHY Protocol Data Units (PPDU), according toan embodiment.

FIG. 6B shows a Table 1 disclosing additional properties of fields ofthe HE PPDU frame of FIG. 6A, according to an embodiment.

FIG. 7 illustrates communications of a BSS during a TransmissionOpportunity (TXOP), according to an embodiment.

FIG. 8 illustrates operation of a station having two NAVs duringcascaded UL MU operations, according to an embodiment.

FIG. 9A illustrates operations of NAVs in first and second BSSs BSS1 andBSS2, according to an embodiment.

FIG. 9B further illustrates operations of NAVs in first and second BSSsBSS1 and BSS2, according to an embodiment.

FIG. 9C further illustrates operations of NAVs in first and second BSSsBSS1 and BSS2, according to an embodiment.

FIG. 10 illustrates a process for determining whether a frame is anInter-BSS or Intra-BSS frame, according to an embodiment.

FIG. 11 illustrates a process for determining whether a frame is anInter-BSS or Intra-BSS frame, according to another embodiment.

FIG. 12A illustrates a frame exchange and NAV operations relatedthereto, according to an embodiment.

FIG. 12B illustrates another frame exchange and NAV operations relatedthereto, according to an embodiment.

FIG. 13 illustrates a process for determining whether a frame is anInter-BSS or Intra-BSS frame, according to another embodiment.

FIG. 14 illustrates a process for determining whether a frame is anInter-BSS or Intra-BSS frame, according to another embodiment.

FIG. 15 illustrates a frame exchange and NAV operations related thereto,according to another embodiment.

DETAILED DESCRIPTION

The technology described herein relates generally to wirelessnetworking. More particularly, the technology relates to techniques forintra-BSS and inter BSS frame detection.

In the following detailed description, certain illustrative embodimentshave been illustrated and described. As those skilled in the art wouldrealize, these embodiments are capable of modification in variousdifferent ways without departing from the scope of the presentdisclosure. Accordingly, the drawings and description are to be regardedas illustrative in nature and not restrictive. Like reference numeralsdesignate like elements in the specification.

FIG. 1 illustrates wireless networks according to an embodiment. Thewireless networks includes first and second infrastructure Basic ServiceSets (BSSs) 100 and 120 of Wireless Local Area Networks (WLANs). In an802.11 WLAN, the BSS provides the basic organizational unit andtypically includes an Access Point (AP) and one or more associatedstations (STAs).

The first BSS 100 includes a first Access Point 102 (also referred to asAP1) wirelessly communicating with first, second, third, and fourthwireless devices (or stations) 104, 106, 108, and 110 (also referred toas stations STA1, STA2, STA3, and STA4, respectively). The second BSS120 includes a second AP 122 (also referred to as AP2) and a fifthdevice (or station) 124 (also referred to as station STA5). The wirelessdevices may each include a medium access control (MAC) layer and aphysical (PHY) layer according to an IEEE 802.11 standard.

Although FIG. 1 shows the first BSS 100 including only the first tofourth stations STA1 to STA4 and the second BSS 120 including only thefifth station STA5, embodiments are not limited thereto and may compriseBSSs including any number of stations.

The first AP 102 is a station, that is, a STA, configured to control andcoordinate functions of the BSS 100. The first AP 102 may transmitinformation to a single station selected from the plurality of stationsSTA1 to STA4 in the first BSS 100 using a single frame, or maysimultaneously transmit information to two or more of the stations STA1to STA4 in the first BSS 100 using either a single Orthogonal FrequencyDivision Multiplexing (OFDM) broadcast frame, a single OFDM Multi-UserMulti-Input-Multi-Output (MU-MIMO) transmission, a single OrthogonalFrequency Division Multiple Access (OFDMA) frame, or a single MU-MIMOOFDMA frame.

The stations STA1 to STA4 may each transmit data to the first AP 102using a single frame, or transmit information to and receive informationfrom each other using a single frame. Two or more of the stations STA1to STA4 may simultaneously transmit data to the first AP 102 using anUplink (UL) OFDMA frame, an UL MU-MIMO frame, or an UL MU-MIMO OFDMAframe.

In another embodiment, the first AP 102 may be absent and the stationsSTA1 to STA4 may be in an ad-hoc network.

The second AP 122 is a station configured to control and coordinatefunctions of the second BSS 120. The second AP 122 may transmitinformation to the fifth station STA5 in the second BSS 120 using asingle frame, or may simultaneously transmit information to two or morestations (not shown) of the second BSS 120 using either a single OFDMbroadcast frame, a single OFDM MU-MIMO transmission, a single OFDMAframe, or a single MU-MIMO OFDMA frame.

The fifth station STA5 may transmit data to the second AP 122 using asingle frame. Two or more of the stations (not shown) of the second BSS120 may simultaneously transmit data to the second AP 122 using anUplink (UL) OFDMA frame, an UL MU-MIMO frame, or an UL MU-MIMO OFDMAframe.

FIG. 1 shows a first intra-BSS Down-Link (DL) transmission 114 and afirst intra-BSS Up-Link (UL) transmission 112 of the first BSS 100, andshows a second intra-BSS DL transmission 126 and a second intra-BSS ULtransmission 128 of the second BSS 120. Intra-BSS transmissions aretransmissions between an AP and stations associated with the BSS thatthe AP controls or between two stations associated with the same BSS.

FIG. 1 also shows first and second inter-BSS transmissions 128-i and126-i. Inter-BSS transmissions are transmissions transmitted by an AP orstation of one BSS and received by an AP or station of another BSS.Here, the first inter-BSS transmission 128-i is an interferingtransmission, received by but not targeted to the third station STA3associated with the first BSS 100, that was produced as a result of thetransmission of the second intra-BSS UL transmission 128 by the fifthstation STA5 associated with the second BSS 120. The second inter-BSStransmission 126-i is an interfering transmission, received by but nottargeted to the fourth station STA4 associated with the first BSS 100,that was produced as a result of the transmission of the secondintra-BSS DL transmission 126 by the second AP 122 that controls thesecond BSS 120.

The third and fourth stations STA3 and STA4 are located in anOverlapping BSS (OBSS) area 140 of the first and second BSSs 100 and120. Stations in the OBSS area 140 may receive transmission from bothdevices associated with the first BSS 100 and devices associated withthe second BSS 120. Transmissions of the stations in the OBSS area 140may also interfere with transmissions of both the first BSS 100 and thesecond BSS 120 under some circumstances.

Each of the stations STA1 to STA4 and the AP 102 includes a processorand a transceiver, and may further include a user interface and adisplay device.

The processor is configured to generate a frame to be transmittedthrough a wireless network, to process a frame received through thewireless network, and to execute protocols of the wireless network. Theprocessor may perform some or all of its functions by executing computerprogramming instructions stored on a non-transitory computer-readablemedium.

The transceiver represents a unit functionally connected to theprocessor, and designed to transmit and receive a frame through thewireless network. The transceiver may include a single component thatperforms the functions of transmitting and receiving, or two separatecomponents each performing one of such functions.

The processor and transceiver of the stations STA1 to STA5, the first AP102, and the second AP 122 may be respectively implemented usinghardware components, software components, or both.

The first and second APs 102 and 122 may each be or include a WLANrouter, a stand-alone Access Point, a WLAN bridge, a Light-Weight AccessPoint (LWAP) managed by a WLAN controller, and the like. In addition, adevice such as a personal computer, tablet computer, or cellular phonemay configured able to operate as the first or second APs 102 or 122,such as when a cellular phone is configured to operate as a wireless“hot spot.”

Each of the stations STA1 to STA5 may be or may include a desktopcomputer, a laptop computer, a tablet PC, a wireless phone, a mobilephone, a smart phone, an e-book reader, a Portable Multimedia Player(PMP), a portable game console, a navigation system, a digital camera, aDigital Multimedia Broadcasting (DMB) player, a digital audio recorder,a digital audio player, a digital picture recorder, a digital pictureplayer, a digital video recorder, a digital video player, and the like.

The present disclosure may be applied to WLAN systems according to IEEE802.11 standards but embodiments are not limited thereto.

In IEEE 802.11 standards, frames exchanged between stations (includingaccess points) are classified into management frames, control frames,and data frames. A management frame may be a frame used for exchangingmanagement information that is not forwarded to a higher layer of acommunication protocol stack. A control frame may be a frame used forcontrolling access to a medium. A data frame may be a frame used fortransmitting data to be forwarded to the higher layer of thecommunication protocol stack.

A type and subtype of a frame may be identified using a type fieldand/or a subtype field included in a control field of the frame, asprescribed in the applicable standard.

FIG. 2 illustrates a schematic block diagram of a wireless device 200according to an embodiment. The wireless or WLAN device 200 may beincluded in the APs 102 or 122 or any of the stations STA1 to STA5 inFIG. 1. The WLAN device 200 includes a baseband processor 210, a radiofrequency (RF) transceiver 240, an antenna unit 250, a storage device(e.g., memory) 232, one or more input interfaces 234, and one or moreoutput interfaces 236. The baseband processor 210, the memory 232, theinput interfaces 234, the output interfaces 236, and the RF transceiver240 may communicate with each other via a bus 260.

The baseband processor 210 performs baseband signal processing, andincludes a MAC processor 212 and a PHY processor 222. The basebandprocessor 210 may utilize the memory 232, which may include anon-transitory computer readable medium having software (e.g., computerprogramming instructions) and data stored therein.

In an embodiment, the MAC processor 212 includes a MAC softwareprocessing unit 214 and a MAC hardware processing unit 216. The MACsoftware processing unit 214 may implement a first plurality offunctions of the MAC layer by executing MAC software, which may beincluded in the software stored in the memory 232. The MAC hardwareprocessing unit 216 may implement a second plurality of functions of theMAC layer in special-purpose hardware. However, the MAC processor 212 isnot limited thereto. For example, the MAC processor 212 may beconfigured to perform the first and second plurality of functionsentirely in software or entirely in hardware according to animplementation.

The PHY processor 222 includes a transmitting signal processing unit(SPU) 224 and a receiving SPU 226. The PHY processor 222 implements aplurality of functions of the PHY layer. These functions may beperformed in software, hardware, or a combination thereof according toan implementation.

Functions performed by the transmitting SPU 224 may include one or moreof Forward Error Correction (FEC) encoding, stream parsing into one ormore spatial streams, diversity encoding of the spatial streams into aplurality of space-time streams, spatial mapping of the space-timestreams to transmit chains, inverse Fourier Transform (iFT) computation,Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and thelike. Functions performed by the receiving SPU 226 may include inversesof the functions performed by the transmitting SPU 224, such as GIremoval, Fourier Transform computation, and the like.

The RF transceiver 240 includes an RF transmitter 242 and an RF receiver244. The RF transceiver 240 is configured to transmit first informationreceived from the baseband processor 210 to the WLAN, and provide secondinformation received from the WLAN to the baseband processor 210.

The antenna unit 250 includes one or more antennas. When Multiple-InputMultiple-Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, the antennaunit 250 may include a plurality of antennas. In an embodiment, theantennas in the antenna unit 250 may operate as a beam-formed antennaarray. In an embodiment, the antennas in the antenna unit 250 may bedirectional antennas, which may be fixed or steerable.

The input interfaces 234 receive information from a user, and the outputinterfaces 236 output information to the user. The input interfaces 234may include one or more of a keyboard, keypad, mouse, touchscreen,microphone, and the like. The output interfaces 236 may include one ormore of a display device, touch screen, speaker, and the like.

As described herein, many functions of the WLAN device 200 may beimplemented in either hardware or software. Which functions areimplemented in software and which functions are implemented in hardwarewill vary according to constraints imposed on a design. The constraintsmay include one or more of design cost, manufacturing cost, time tomarket, power consumption, available semiconductor technology, and soon.

As described herein, a wide variety of electronic devices, circuits,firmware, software, and combinations thereof may be used to implementthe functions of the components of the WLAN device 200. Furthermore, theWLAN device 200 may include other components, such as applicationprocessors, storage interfaces, clock generator circuits, power supplycircuits, and the like, which have been omitted in the interest ofbrevity.

FIG. 3A illustrates components of a wireless device configured totransmit data according to an embodiment, including a Transmitting (Tx)SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In anembodiment, the TxSP 324, the RF transmitter 342, and the antenna 352correspond to the transmitting SPU 224, the RF transmitter 242, and anantenna of the antenna unit 250 of FIG. 2, respectively.

The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304,an inverse Fourier transformer (IFT) 306, and a guard interval (GI)inserter 308.

The encoder 300 receives and encodes input data DATA. In an embodiment,the encoder 300 includes a forward error correction (FEC) encoder. TheFEC encoder may include a binary convolutional code (BCC) encoderfollowed by a puncturing device. The FEC encoder may include alow-density parity-check (LDPC) encoder.

The TxSP 324 may further include a scrambler for scrambling the inputdata before the encoding is performed by the encoder 300 to reduce theprobability of long sequences of 0s or 1s. When the encoder 300 performsthe BCC encoding, the TxSP 324 may further include an encoder parser fordemultiplexing the scrambled bits among a plurality of BCC encoders. IfLDPC encoding is used in the encoder, the TxSP 324 may not use theencoder parser.

The interleaver 302 interleaves the bits of each stream output from theencoder 300 to change an order of bits therein. The interleaver 302 mayapply the interleaving only when the encoder 300 performs the BCCencoding, and otherwise may output the stream output from the encoder300 without changing the order of the bits therein.

The mapper 304 maps the sequence of bits output from the interleaver 302to constellation points. If the encoder 300 performed LDPC encoding, themapper 304 may also perform LDPC tone mapping in addition to theconstellation mapping.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324may include a plurality of interleavers 302 and a plurality of mappers304 according to a number of spatial streams (NSS) of the transmission.The TxSP 324 may further include a stream parser for dividing the outputof the encoder 300 into blocks and may respectively send the blocks todifferent interleavers 302 or mappers 304. The TxSP 324 may furtherinclude a space-time block code (STBC) encoder for spreading theconstellation points from the spatial streams into a number ofspace-time streams (NSTS) and a spatial mapper for mapping thespace-time streams to transmit chains. The spatial mapper may use directmapping, spatial expansion, or beamforming.

The IFT 306 converts a block of the constellation points output from themapper 304 (or, when MIMO or MU-MIMO is performed, the spatial mapper)to a time domain block (i.e., a symbol) by using an inverse discreteFourier transform (IDFT) or an inverse fast Fourier transform (IFFT). Ifthe STBC encoder and the spatial mapper are used, the IFT 306 may beprovided for each transmit chain.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324may insert cyclic shift diversities (CSDs) to prevent unintentionalbeamforming. The TxSP 324 may perform the insertion of the CSD before orafter the IFT 306. The CSD may be specified per transmit chain or may bespecified per space-time stream. Alternatively, the CSD may be appliedas a part of the spatial mapper.

When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocksbefore the spatial mapper may be provided for each user.

The GI inserter 308 prepends a GI to each symbol produced by the IFT306. Each GI may include a Cyclic Prefix (CP) corresponding to arepeated portion of the end of the symbol that the GI precedes. The TxSP324 may optionally perform windowing to smooth edges of each symbolafter inserting the GI.

The RF transmitter 342 converts the symbols into an RF signal andtransmits the RF signal via the antenna 352. When the TxSP 324 performsa MIMO or MU-MIMO transmission, the GI inserter 308 and the RFtransmitter 342 may be provided for each transmit chain.

FIG. 3B illustrates components of a wireless device configured toreceive data according to an embodiment, including a Receiver (Rx) SPU(RxSP) 326, an RF receiver 344, and an antenna 354. In an embodiment,the RxSP 326, RF receiver 344, and antenna 354 may correspond to thereceiving SPU 226, the RF receiver 244, and an antenna of the antennaunit 250 of FIG. 2, respectively.

The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316,a demapper 314, a deinterleaver 312, and a decoder 310.

The RF receiver 344 receives an RF signal via the antenna 354 andconverts the RF signal into symbols. The GI remover 318 removes the GIfrom each of the symbols. When the received transmission is a MIMO orMU-MIMO transmission, the RF receiver 344 and the GI remover 318 may beprovided for each receive chain.

The FT 316 converts each symbol (that is, each time domain block) into afrequency domain block of constellation points by using a discreteFourier transform (DFT) or a fast Fourier transform (FFT). The FT 316may be provided for each receive chain.

When the received transmission is the MIMO or MU-MIMO transmission, theRxSP 326 may include a spatial demapper for converting the respectiveoutputs of the FTs 316 of the receiver chains to constellation points ofa plurality of space-time streams, and an STBC decoder for despreadingthe constellation points from the space-time streams into one or morespatial streams.

The demapper 314 demaps the constellation points output from the FT 316or the STBC decoder to bit streams. If the received transmission wasencoded using the LDPC encoding, the demapper 314 may further performLDPC tone demapping before performing the constellation demapping.

The deinterleaver 312 deinterleaves the bits of each stream output fromthe demapper 314. The deinterleaver 312 may perform the deinterleavingonly when the received transmission was encoded using the BCC encoding,and otherwise may output the stream output by the demapper 314 withoutperforming deinterleaving.

When the received transmission is the MIMO or MU-MIMO transmission, theRxSP 326 may use a plurality of demappers 314 and a plurality ofdeinterleavers 312 corresponding to the number of spatial streams of thetransmission. In this case, the RxSP 326 may further include a streamdeparser for combining the streams output from the deinterleavers 312.

The decoder 310 decodes the streams output from the deinterleaver 312 orthe stream deparser. In an embodiment, the decoder 312 includes an FECdecoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

The RxSP 326 may further include a descrambler for descrambling thedecoded data. When the decoder 310 performs the BCC decoding, the RxSP326 may further include an encoder deparser for multiplexing the datadecoded by a plurality of BCC decoders. When the decoder 310 performsthe LDPC decoding, the RxSP 326 may not use the encoder deparser.

Before making a transmission, wireless devices such as wireless device200 will assess the availability of the wireless medium using ClearChannel Assessment (CCA). If the medium is occupied, CCA may determinethat it is busy, while if the medium is available, CCA determines thatit is idle.

The PHY entity for IEEE Std 802.11 is based on Orthogonal FrequencyDivision Multiplexing (OFDM) or Orthogonal Frequency Division MultipleAccess (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA iscapable of transmitting and receiving Physical Layer Protocol Data Units(PPDUs) that are compliant with the mandatory PHY specifications. A PHYspecification defines a set of Modulation and Coding Schemes (MCS) and amaximum number of spatial streams. Some PHY entities define downlink(DL) and uplink (UL) Multi-User (MU) transmissions having a maximumnumber of space-time streams (STS) per user and employing up to apredetermined total number of STSs.

FIG. 4 illustrates Inter-Frame Space (IFS) relationships. FIG. 4illustrates a Short IFS (SIFS), a Point Coordination Function (PCF) IFS(PIFS), a Distributed Coordination Function (DCF) IFS (DIFS), and anArbitration IFSs corresponding to an Access Category (AC) ‘i’ (AIFS[i]).FIG. 4 also illustrates a slot time.

A data frame is used for transmission of data forwarded to a higherlayer. The WLAN device transmits the data frame after performing backoffif a DIFS has elapsed during which DIFS the medium has been idle.

A management frame is used for exchanging management information, whichis not forwarded to the higher layer. Subtype frames of the managementframe include a beacon frame, an association request/response frame, aprobe request/response frame, and an authentication request/responseframe.

A control frame is used for controlling access to the medium. Subtypeframes of the control frame include a request to send (RTS) frame, aclear to send (CTS) frame, and an acknowledgement (ACK) frame.

When the control frame is not a response frame of another frame, theWLAN device transmits the control frame after performing backoff if aDIFS has elapsed during which DIFS the medium has been idle. When thecontrol frame is the response frame of another frame, the WLAN devicetransmits the control frame after a SIFS has elapsed without performingbackoff or checking whether the medium is idle.

A WLAN device that supports a Quality of Service (QoS) functionality(that is, a QoS station) may transmit the frame after performing backoffif an AIFS for an associated access category (AC), (AIFS[AC]), haselapsed. When transmitted by the QoS station, any of the data frame, themanagement frame, and the control frame which is not the response framemay use the AIFS[AC] of the AC of the transmitted frame.

A WLAN device may perform a backoff procedure when the WLAN device thatis ready to transfer a frame finds the medium busy. In addition, a WLANdevice operating according to the IEEE 802.11n and 802.11ac standardsmay perform the backoff procedure when the WLAN device infers that atransmission of a frame by the WLAN device has failed.

The backoff procedure includes determining a random backoff timecomposed of N backoff slots, each backoff slot having a duration equalto a slot time and N being an integer number greater than or equal tozero. The backoff time may be determined according to a length of aContention Window (CW). In an embodiment, the backoff time may bedetermined according to an AC of the frame. All backoff slots occurfollowing a DIFS or Extended IFS (EIFS) period during which the mediumis determined to be idle for the duration of the period.

When the WLAN device detects no medium activity for the duration of aparticular backoff slot, the backoff procedure shall decrement thebackoff time by the slot time. When the WLAN determines that the mediumis busy during a backoff slot, the backoff procedure is suspended untilthe medium is again determined to be idle for the duration of a DIFS orEIFS period. The WLAN device may perform transmission or retransmissionof the frame when the backoff timer reaches zero.

The backoff procedure operates so that when multiple WLAN devices aredeferring and execute the backoff procedure, each WLAN device may selecta backoff time using a random function, and the WLAN device selectingthe smallest backoff time may win the contention, reducing theprobability of a collision.

FIG. 5 illustrates a Carrier Sense Multiple Access/Collision Avoidance(CSMA/CA) based frame transmission procedure for avoiding collisionbetween frames in a channel according to an embodiment. FIG. 5 shows afirst station STA1 transmitting data, a second station STA2 receivingthe data, and a third station STA3 that may be located in an area wherea frame transmitted from the STA1, a frame transmitted from the secondstation STA2, or both can be received. The stations STA1, STA2, and STA3may be WLAN devices.

The STA1 may determine whether the channel is busy by carrier sensing.The STA1 may determine the channel occupation based on an energy levelin the channel or an autocorrelation of signals in the channel, or maydetermine the channel occupation by using a network allocation vector(NAV) timer.

After determining that the channel is not used by other devices (thatis, that the channel is IDLE) during a DIFS (and performing backoff ifrequired), the STA1 may transmit a Ready-To-Send (RTS) frame to thesecond station STA2. Upon receiving the RTS frame, after a SIFS thesecond station STA2 may transmit a Clear-To-Send (CTS) frame as aresponse of the RTS frame. If Dual-CTS is enabled and the second stationSTA2 is an AP, the AP may send two CTS frames in response to the RTSframe: a first CTS frame in the legacy non-HT format, and a second CTSframe in the HT format.

When the third station STA3 receives the RTS frame, it may set a NAVtimer of the third station STA3 for a transmission duration ofsubsequently transmitted frames (for example, a duration of SIFS+CTSframe duration+SIFS+data frame duration+SIFS+ACK frame duration) usingduration information included in the RTS frame. When the third stationSTA3 receives the CTS frame, it may set the NAV timer of the thirdstation STA3 for a transmission duration of subsequently transmittedframes using duration information included in the CTS frame. Uponreceiving a new frame before the NAV timer expires, the third stationSTA3 may update the NAV timer of the third station STA3 by usingduration information included in the new frame. The third station STA3does not attempt to access the channel until the NAV timer expires.

When the STA1 receives the CTS frame from the second station STA2, itmay transmit a data frame to the second station STA2 after SIFS elapsesfrom a time when the CTS frame has been completely received. Uponsuccessfully receiving the data frame, the second station STA2 maytransmit an ACK frame as a response of the data frame after SIFSelapses.

When the NAV timer expires, the third station STA3 may determine whetherthe channel is busy using the carrier sensing. Upon determining that thechannel is not used by other devices during a DIFS after the NAV timerhas expired, the third station STA3 may attempt to access the channelafter a contention window according to a backoff process elapses.

When Dual-CTS is enabled, a station that has obtained a transmissionopportunity (TXOP) and that has no data to transmit may transmit aCF-End frame to cut short the TXOP. An AP receiving a CF-End framehaving a Basic Service Set Identifier (BSSID) of the AP as a destinationaddress may respond by transmitting two more CF-End frames: a firstCF-End frame using Space Time Block Coding (STBC) and a second CF-Endframe using non-STBC. A station receiving a CF-End frame resets its NAVtimer to 0 at the end of the PPDU containing the CF-End frame.

FIG. 5 shows the second station STA1 transmitting an ACK frame toacknowledge the successful reception of a frame by the recipient.

The PHY entity for IEEE Std 802.11 is based on Orthogonal FrequencyDivision Multiplexing (OFDM) or Orthogonal Frequency Division MultipleAccess (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA iscapable of transmitting and receiving PHY Protocol Data Units (PPDUs)that are compliant with the mandatory PHY specifications.

A PHY entity may provide support for 20 MHz, 40 MHz, 80 MHz, and 160 MHzcontiguous channel widths and support for an 80+80 MHz non-contiguouschannel width. Each channel includes a plurality of subcarriers, whichmay also be referred to as tones.

A PHY entity may define fields denoted as Legacy Signal (L-SIG), SignalA (SIG-A), and Signal B (SIG-B) within which some necessary informationabout PHY Service Data Unit (PSDU) attributes are communicated. Forexample, a High Efficiency (HE) PHY entity may define an L-SIG field, anHE-SIG-A field, and an HE-SIG-B field.

The descriptions below, for sake of completeness and brevity, refer toOFDM-based 802.11 technology. Unless otherwise indicated, a stationrefers to a non-AP HE STA, and an AP refers to an HE AP.

In the IEEE Std 802.11ac, SIG-A and SIG-B fields are called VHT SIG-Aand VHT SIG-B fields. Hereinafter, IEEE Std 802.11ax SIG-A and SIG-Bfields are respectively referred to as HE-SIG-A and HE-SIG-B fields.

FIG. 6A illustrates an HE PPDU 600 according to an embodiment. Atransmitting station generates the HE PPDU frame 600 and transmits it toone or more receiving stations. The receiving stations receive, detect,and process the HE PPDU frame 600.

The HE PPDU frame 600 includes a Legacy Short Training Field (L-STF)field 602, a Legacy (i.e., a Non-High Throughput (Non-HT)) Long TrainingField (L-LTF) 604, a Legacy Signal (L-SIG) field 606, and a RepeatedL-SIG field (RL-SIG) 608, which together comprise a legacy preamble 601.The L-STF 604 of a non-trigger-based PPDU has a periodicity of 0.8 μswith 10 periods.

The HE PPDU frame 600 also includes an HE-SIG-A field 610, an optionalHE-SIG-B field 612, an HE-STF 614, an HE-LTF 616, and an HE-Data field618.

The legacy preamble 601, the HE-SIG-A field 610, and the HE-SIG-B field612 when present, comprise a first part of the HE PPDU frame 600. In anembodiment, the first part of the HE PPDU frame 600 is decoded using a64-element Discrete Fourier Transform (DFT), having a basic subcarrierspacing of 312.5 KHz.

The HE-SIG-A field 610 is duplicated on each 20 MHz segment after thelegacy preamble to indicate common control information. The HE-SIG-Afield 610 includes a plurality of OFDM HE-SIG-A symbols 620 each havinga duration (including a Guard Interval (GI)) of 4 μs. A number of theHE-SIG-A symbols 620 in the HE-SIG-A field 610 is indicated byN_(HESIGA) and is either 2 or 4.

The HE-SIG-B field 612 is included in Down-Link (DL) Multi-User (MU)PPDUs. The HE-SIG-B field 612 includes a plurality of OFDM HE-SIG-Bsymbols 622 each having a duration including a Guard Interval (GI) of 4μs. In embodiments, Single User (SU) PPDUs, Up-Link (UL) MU PPDUs, orboth do not include the HE-SIG-B field 612. A number of the HE-SIG-Bsymbols 622 in the HE-SIG-B field 612 is indicated by N_(HESIGB) and isvariable.

When the HE PPDU 600 has a bandwidth of 40 MHz or more, the HE-SIG-Bfield 612 may be transmitted in first and second HE-SIG-B channels 1 and2. The HE-SIG-B field in the HE-SIG-B channel 1 is referred to as theHE-SIG-B1 field, and the HE-SIG-B field in the HE-SIG-B channel 2 isreferred to as the HE-SIG-B2 field. The RE-SIG-B1 field and theHE-SIG-B2 field are communicated using different 20 MHz bandwidths ofthe HE PPDU 600, and may contain different information. Within thisdocument, the term “HE-SIG-B field” may refer to an HE-SIG-B field of a20 MHz PPDU, or to either or both of an RE-SIG-B1 field or HE-SIG-B2field of a 40 MHz or more PPDU.

An HE-STF 614 of a non-trigger-based PPDU has a periodicity of 0.8 μswith 5 periods. A non-trigger-based PPDU is a PPDU that is not sent inresponse to a trigger frame. An HE-STF 614 of a trigger-based PPDU has aperiodicity of 1.6 μs with 5 periods. Trigger-based PPDUs include ULPPDUs sent in response to respective trigger frames.

The HE-LTF 616 includes one or more OFDM HE-LTF symbols 626 each havinga duration of 12.8 μs plus a Guard Interval (GI). The HE PPDU frame 600may support a 2×LTF mode and a 4×LTF mode. In the 2×LTF mode, an HE-LTFsymbol 626 excluding a Guard Interval (GI) is equivalent to modulatingevery other tone in an OFDM symbol of 12.8 μs excluding the GI, and thenremoving the second half of the OFDM symbol in a time domain. A numberof the HE-LTF symbols 626 in the HE-LTF field 616 is indicated byN_(HELTF), and is equal to 1, 2, 4, 6, or 8.

The HE-Data field 618 includes one or more OFDM HE-Data symbols 628 eachhaving a duration of 12.8 μs plus a Guard Interval (GI). A number of theHE-Data symbols 628 in the HE-Data field 618 is indicated by N_(DATA)and is variable.

FIG. 6B shows a Table 1 indicating additional properties of the fieldsof the HE PPDU frame 600 of FIG. 6A, according to an embodiment.

The descriptions below, for sake of completeness and brevity, refer toOFDMA-based 802.11 technology. Unless otherwise indicated, a stationrefers to a non-AP HE STA, and an AP refers to an HE AP.

Embodiments include a station of an HE WLAN system, wherein the stationmaintains two NAV values. The station maintains an Intra-BSS NAV, whichmay be referred to as NAV_(intra-BSS), managed according to frames thatare identified as intra-BSS frames, and an Inter-BSS NAV, which may bereferred to as NAV_(inter-BSS), managed according to frames that areidentified as inter-BSS frames or that cannot be determined to beintra-BSS or inter-BSS frames.

Some frames, such as legacy Clear-to-Send (CTS) frames and legacyAcknowledgment (ACK) frames, do not contain a transmitter address (TA)identifying the sender of the frame or an identifier of the BSS that thesender of the frame is associated with. A station receiving such framesmay not be able to determine whether they are intra-BSS frames orintra-BSS frames based on the lack of this information in the frame. Asa result, in some circumstances, a station receiving such frames cannotdetermine whether the NAV_(inter-BSS) or the NAV_(intra-BSS) is thecorrect NAV to update.

Since the Inter-BSS NAV NAV_(inter-BSS) could therefore on occasion beset or updated by an intra-BSS frame, there may be some unintendedprocedures that cause the HE WLAN to operate less efficiently thanotherwise would be the case.

The distributed nature of channel access networks, such as IEEE 802.11WLANs, makes the carrier sense mechanism important for reducing a numberof collisions occurring in the WLAN. The physical carrier sense of oneSTA is responsible for detecting the transmissions of other STAs. But itmay be impossible to detect every single case in some circumstances. Forexample, a first STA that is a large distance away from a second STA maysee the medium as idle even though the second STA (known as the “hiddennode”) is transmitting to an AP. As a result the first STA may begintransmitting to the AP. The transmissions of the first and second STAsmay then collide at the AP, causing one or both transmissions to fail.

A NAV (Network Allocation Vector) is used in the IEEE 802.11 standardsto overcome this “hidden node” problem by providing a “virtual carriersense” capability. However, as the IEEE 802.11 standard evolves toinclude multiple users' simultaneous transmission/reception scheduledwithin a BSS (such as UL/DL multi-user (MU) transmissions performed in acascading manner), it may be advantageous to use a modified or newlydefined mechanism for virtual carrier sensing.

As used herein, an MU transmission refers to transmissions in whichmultiple frames are transmitted to or from multiple STAs simultaneouslyusing different resources. Examples of different resources includedifferent frequency resources in an OFDMA transmission and differentspatial streams in an MU MIMO transmission. DL OFDMA transmissions, DLMU-MIMO transmissions, UL OFDMA transmissions, and UL MU-MIMOtransmissions are examples of MU transmissions.

As used herein, a transmission or frame is targeted or addressed to astation when the transmission or frame includes in a receiver addressfield a receiver address of the station.

The IEEE 802.11ax standard currently being drafted supports DL MUtransmissions and UL MU transmissions. UL MU PPDUs (MU-MIMO or OFDMA)are sent as a response to a Trigger frame transmitted by the AP. Thetrigger frame may have enough station-specific information and assignedresource units to identify the stations which are to participate in theUL MU PPDUs. In addition, the IEEE 802.11ax standard may includemechanisms for efficiently multiplexing acknowledgements transmission inresponse to a DL or UL MU PPDU.

FIG. 7 illustrates communications of a BSS during a TransmissionOpportunity (TXOP), according to an embodiment. In an embodiment, theTXOP is a TXOP in a Target Wake Time (TWT) Service Period.

During the TXOP, an AP transmits a first DL MU PPDU 702 and a firstTrigger Frame 704. The first Trigger Frame 704 includes a cascadeindicator indicating that the AP will transmit another trigger framewithin the TXOP. The first Trigger Frame 704 indicates a first set ofone or more stations. In an embodiment, the first Trigger Frame 704 isincluded in the first DL MU PPDU 702.

In response to the first Trigger Frame 704, the first set of one or morestations transmit a first UL MU PPDU 706.

The AP then transmits a second DL MU PPDU 708 and a second Trigger Frame710. The Trigger Frame 710 indicates a second set of one or morestations. In an embodiment, the second Trigger Frame 710 includes acascade indicator indicating that the AP will transmit another triggerframe within the TXOP. In an embodiment, the second Trigger Frame 710 isincluded in the second DL MU PPDU 708.

In response to the second Trigger Frame 710, the second set of one ormore stations transmit a second UL MU PPDU 712. The second set ofstations may include zero or more stations from the first set ofstations and may include zero or more stations not included in the firstset of stations.

The cascading of DL MU transmissions and UL MU transmissions within aTXOP, such as shown in FIG. 1, allows an AP and its associated stationsopportunities to exchange multiple types of frames efficiently andquickly to support MU transmission.

To increase system throughput, the IEEE 802.11ax standard currentlybeing drafted has increased a Clear Channel Assessment (CCA) thresholdvalue to enable more aggressive channel access. However, increasing theCCA threshold value may result in more frequent packet collision anddegradation of a Quality of Service (QoS) of packet delivery. However,if a first station assesses the wireless medium and a frame thatoccupies the wireless medium is between a second station and an AP ofthe BSS that the first station is associated with, then even if the CCAthreshold value is increased enough to permit the first station toinitiates transmission to the AP, the transmission will not besuccessful because the AP is currently in the middle oftransmission/reception with the second station.

Therefore, it may be advantageous to indicate CCA related information,spatial reuse related information, or both in the physical layer headerof a frame so that stations that identify a start of a frame can utilizethe CCA or spatial reuse related information in determining whether toadjust CCA threshold value.

One example of indicating spatial reuse related information in aphysical layer header is a Color field of a frame. Color field ispartial BSS information regarding which BSS a transmitter of a framebelongs to. When a station identifies a start of a frame as part ofwireless medium assessment operation, the station checks the Color fieldof the frame. If the Color field indicates a same Color as the Color ofthe BSS that the station is associated with (i.e., the Color of thestation), the stations assesses the wireless medium as BUSY. However, ifthe Color field indicates a different Color than the Color of thestation, the station compares a received signal strength of the framewith a first threshold (for example, an OBSS_PD level), and assesses thewireless medium as BUSY only if the received signal strength is abovethe first threshold.

Under the current rules for HE WLAN systems, a STA maintains twodifferent NAVs. The first is a NAV (NAV_(intra-BSS)) for intra-BSSframes, while the second is a NAV (NAV_(inter-BSS)) for inter-BSS frameor frames that a station is unable to determine to be an Intra-BSS orInter-BSS frame.

A station may be unable to determine whether a frame is an Intra-BSS orInter-BSS frame because there is no valid BSS information (such as aColor field in a PHY field or a MAC address in a MAC field) to classifythe frame as originating in the BSS that the station is associated with(said BSS referred to hereinafter as myBSS).

FIG. 8 illustrates operation of a station having two NAVs during UL MUoperations, according to an embodiment. The operations are performed byan Access Point AP and first to fourth stations STA1 to STA4. Thestations STA1 to STA4 are all associated with the BSS controlled by theAP.

In the example of FIG. 8, the fourth station STA4 had, in response toand using a value received in a prior Inter-BSS frame, already set anInter-BSS NAV NAV_(inter-BSS) of the fourth station STA4 before the APtransmitted a first Trigger frame 802.

The AP transmits a first Trigger frame 802 soliciting the stations STA1,STA2, STA3, and STA4 in an UL MU manner. The stations STA1, STA2, andSTA3 receive the first Trigger frame 802 but the fourth station STA4does not. In response to receiving the first Trigger frame 802, thestations STA1, STA2, and STA3 participate in a first UL MU transmission804 by respectively transmitting UL MU response frames 804A, 804B, and804C to the AP. The AP then transmits a first MU Block ACK (BA) frame806 in response to receiving the first UL MU transmission 804.

The fourth station STA4 receives one or more of the UL MU responseframes 804A, 804B, and 804C and determines, based on a Color field or aMAC address of the received transmission, that the received one or moreof the UL MU response frames 804A, 804B, and 804C are from the myBSS ofthe fourth station STA4. The fourth station STA4 therefore sets anIntra-BSS NAV NAV_(intra-BSS) of the fourth station STA4 with the valueof a TXOP duration field of the received transmission.

FIG. 8 illustrates a cascaded operation wherein the AP transmits asecond Trigger frame 808 after transmitting the first MU BA frame 806.The second Trigger frame 808 indicates that the stations STA1, STA2,STA3, and STA4 are to participate in the upcoming second UL MUtransmission 810.

The AP cannot override the Inter-BSS NAV NAV_(inter-BSS) set by thefourth station STA4 in response to the prior-received inter-BSS frame.As a result, to protect the busy medium of the other BSS, the fourthSTA4 is not allowed to participate in the second UL MU transmission 810because the Inter-BSS NAV NAV_(inter-BSS) set by the fourth station STA4has not expired at a time at which the second UL MU transmission 810 isto be performed.

As a result, even though the fourth station STA4 receives the secondTrigger frame 808 indicating that the fourth station STA4 is toparticipate in the second UL MU transmission 810, the fourth stationSTA4 does not participate in the second UL MU transmission 810.

In response to the second Trigger frame 808, the first, second, andthird stations STA1, STA2, and STA3 participate in the second UL MUtransmission 810 by respectively transmitting UL MU response frames810A, 810B, and 810C. The AP then transmits a second MU Block ACK (BA)frame 812 in response to receiving the second UL MU transmission 810.

The AP transmits a third Trigger frame 814 after transmitting the secondMU BA frame 812. The third Trigger frame 814 indicates that the stationsSTA1, STA2, STA3, and STA4 are to participate in the upcoming third ULMU transmission 816.

Because the Inter-BSS NAV NAV_(inter-BSS) of the fourth station STA4 hasexpired before the time for the third UL MU transmission 816, and theIntra-BSS NAV NAV_(intra-BSS) being set does not prevent the fourthstation STA4 from responding to a trigger frame from the AP of the BSSit is associated with, the fourth station STA4 is allowed to participatein the third UL MU transmission 816.

Accordingly, in response to the third Trigger frame 814, the first,second, third, and fourth stations STA1, STA2, STA3, and STA4participate in the third UL MU transmission 816 by respectivelytransmitting UL MU response frames 816A, 816B, 816C, and 816D. The APthen transmits a third MU Block ACK (BA) frame 818 in response toreceiving the third UL MU transmission 816.

However, when the Inter-BSS NAV NAV_(inter-BSS) is set or updated by aframe that cannot be determined to be an inter-BSS or inter-BSS frame,there may be unintended and unnecessary restrictions on stationtransmission which could happen frequently in a HE WLAN system andproduce a performance loss.

FIG. 9A illustrates operations of NAVs in first and second BSSs BSS1 andBSS2, according to an embodiment. The first BSS BSS1 includes a first APAP1 and first, second, and third stations STA1, STA2, and STA3. Thesecond BSS BSS2 includes a second AP AP2 and a fifth station STA5.

In the example of FIG. 9A, the third station STA3 is in an OBSS areawhere it may receive frames transmitted by devices in the first BSS BSS1and may receive frames transmitted by devices in the second BSS BSS2.Therefore, when, in the second BSS BSS2, the second AP AP2 and the fifthstation STA 5 exchanges frames in sequence, the third station STA3 candetect those frames because the third station STA3 is close to thesecond AP AP2 and the fifth station STA5 in distance.

in the example of FIG. 9A, the first station STA1 is a TXOP holder ofthe first BSS BSS1. Accordingly, the first station STA1 as the TXOPholder starts a protection mechanism by sending an RTS frame 902 to thefirst AP AP1. The first AP AP1 transmits a CTS frame 904 in response toreceiving the RTS frame 902. After the RTS/CTS sequence exchange,operations in the first BSS BSS1 are contiguous within a TXOP.

In the second BSS BSS2, the second AP transmits a frame 922 including afirst preamble 922-1 and a first payload 922-2.

The second and third stations STA2 and STA3 of the first BSS BSS1 areuntargeted stations. In the example shown in FIG. 9A, the second stationSTA2 receives the CTS frame 904 but not the RTS frame 902. The thirdstation STA3 receives the first preamble 922-1 and the first payload922-2 but does not receive the RTS frame 902 or the CTS frame 904.

In response to receiving the CTS frame 904, the second station STA2 setsa NAV in response to receiving the CTS frame 904, using durationinformation in the CTS frame 904. However, because the CTS frame doesnot include an indication that it was transmitted from a device in thefirst BSS BSS1—such as a Transmitter Address (TA) or a Color—the secondstation STA2 sets its Inter-BSS NAV NAV_(inter-BSS) 912 even though CTSframe 904 is an intra-frame.

Subsequently, the second station STA2 receives the second preamble 906-1and the second payload 906-2 of a frame 906 transmitted by the secondstation STA1. The second station STA2 determines that the frame 906 isan intra-BSS frame using a TA included in the second payload 906-2 orColor included in the second preamble 906-1. As a result, the secondstation STA2 sets its Intra-BSS NAV NAV_(intra-BSS) 914 using durationinformation in the second preamble 906-1 when the second preamble 906-1is valid.

The third station STA3 receives the first preamble 922-1 and the firstpayload 922-2, identifies them as corresponding to an Inter-BSS frame922 using Color included in the second preamble 922-1 and sets itsInter-BSS NAV NAV_(inter-BSS) 916 using duration information in thefirst preamble 922-1 when the second preamble 922-1 is valid.

In response to receiving the second preamble 906 and the second payload906, the first AP AP1 transmits an ACK or BA frame 910 to the firststation STA1.

FIG. 9B further illustrates operations for the example of FIG. 9A,according to an embodiment.

In FIG. 9B when the operations described for FIG. 9A are complete, thefirst station STA1 doesn't have any more data queued for transmission.Accordingly, the first station STA1 transmits a first CF-End frame 930indicating that as the holder of the TXOP, the first station STA1 isexplicitly indicating the completion of its TXOP. A station shallrespond to the reception of a CF-End frame as a NAV_(intra-BSS) reset.For example, the second station STA2 resets its Intra-BSS NAVNAV_(intra-BSS) 912 to 0 at the end of the PPDU containing the firstCF-End frame 930.

In response to receiving the first CF-End frame 930, the first AP AP1may broadcast a second CF-End frame 932 to every station listed as beingin the first BSS BSS1.

The reception of the CF-End frames does not cause the second stationSTA2 to reset the Inter-BSS NAV NAV_(inter-BSS) 914 that was set by theCTS frame 904. As a result, the second station STA2 is spuriouslyprevented from transmitting because the second station STA2 was unableto determine that the CTS frame 904 was an intra-BSS frame.

The reception of a CF-End frame also does not cause the third stationSTA3 to reset the Inter-BSS NAV NAV_(inter-BSS) 916 set by the frame922. This protects the TXOP of the second BSS BSS2 from interferencefrom the third station STA3, which is in the OBSS area.

FIG. 9C further illustrates operations for the example of FIGS. 9A and9B, according to an embodiment.

After transmitting the second CF-End frame 932, the first AP AP1 is theholder of a new TXOP TXOP2 and transmits a trigger frame 934. Thetrigger frame 934 directs the first and second stations STA1 and STA2 totransmit UL MU frames.

In response to the trigger frame 934, the first station STA1 transmits aframe 936.

However, because the Inter-BSS NAV NAV_(inter-BSS) of the second stationSTA2 912 is still set, as previously explained with respect to FIG. 8,the second station STA2 is prohibited from responding to the triggerframe 934.

A similar reduction in potential performance can occur because eventhough an RTS frame or data frame is available to receive correctly, astation may update its Inter-BSS NAV NAV_(inter-BSS) with a value of avalid duration field in a received legacy CTS frame or a received legacyACK frame where technically there is no TA or valid BSS information.

Embodiments include methods for reducing the occurrence of an Inter-BSSNAV NAV_(inter-BSS) being set by an intra-BSS frame, in order to improveWLAN performance. For example, embodiments may store a TA from anintra-BSS frame, and may compare the stored TA to addresses insubsequent frames. Embodiments may determine that subsequent frames areintra-BSS frames when addresses in the subsequence frame respectivelymatch the stored TA.

FIG. 10 illustrates a process 1000 for determining whether a frame is anInter-BSS frame or an Intra-BSS frame, according to an embodiment. Theprocess 1000 may be performed by one or more of the first to fifthstations STA1 to STA5 of FIG. 1.

At S1002, a station (STA0) performing the process 1000 receives, over ashared wireless medium, a first frame (frame 1) from a first station(STA1). The frame was addressed to a station other than STA0, but STA0detected the frame on the shared wireless medium. In an embodiment, thefirst frame is an RTS frame or a data frame.

In an embodiment, the first station is a non-AP station.

At S1004, the process 1000 determines whether the first frame includesvalid BSS information, that is, information that can be used todetermine whether the frame was transmitted by a device associated witha particular BSS. In an embodiment, BSS information includes Colorinformation corresponding to a color of a BSS (i.e., a shortened BSSidentifier), an address of a device (such as a MAC address) that can beused to determine whether the device is associated with the BSS, orboth.

At S1004, when the process 1000 determines that the first frame doesinclude valid BSS information, the process 1000 proceeds to S1006; andwhen the process 1000 determines that the first frame does not includevalid BSS information, the process 1000 proceeds to S1005.

At S1005, the process 1000 updates an inter-BSS NAV using durationinformation included in the first frame, and the process 1000 ends.

At S1006, the process 1000 determines, using the BSS information of thefirst frame, whether the first station, which transmitted the firstframe, is associated with a same BSS (myBSS) that the station STA0performing the process 1000 is associated with; that is, whether thefirst station is in myBSS. When the process 1000 determines that thefirst station is in myBSS, the process 1000 proceeds to S1008; and whenthe process 1000 determines that the first station is not in myBSS, theprocess 1000 proceeds to S1005.

At S1008, the process 1000 stores an address of the first frame as astored address. In an embodiment, the address of the first frame is atransmit address (TA) corresponding to the first station. In anembodiment, at S1008 the process 1000 updates an intra-BSS NAV using theduration information included in the first frame.

At S1010, the station STA0 performing the process 1000 receives a secondframe (frame 2) from a second station (STA2). The frame was addressed toa station other than STA0, but STA0 detected the frame on the sharedwireless medium. In an embodiment, the second station is different fromthe first station. In an embodiment, the second station is an AP.

In an embodiment, the process 1000 receives the second frame within aShort Inter-Frame Spacing (SIFS) of the end of the first frame or withina duration of a frame exchange that includes the first and secondframes.

In an embodiment, the second frame is a CTS or ACK frame having a legacyformat. In an embodiment, the second frame is a CTS or ACK frame havinga non-HE format.

At S1012, the process 1000 determines whether the second frame includesvalid BSS information. When the process 1000 determines that the secondframe does include valid BSS information, the process 1000 proceeds toS1014. When the process 1000 determines that the second frame does notinclude valid BSS information, the process 1000 proceeds to S1016.

At S1014, the process 1000 determines whether the second station is inmyBSS using the BSS information of the second frame. When the secondstation is determined to be in the myBSS, the process 1000 determinesthat the second frame is an intra-BSS frame. Otherwise, the process 1000determines that the second frame is an inter-BSS frame.

In an embodiment, at S1014 the process 1000, using duration informationincluded in the second frame, updates the inter-BSS NAV when the process1000 determines that the second frame is an inter-BSS frame and updatesthe intra-BSS NAV when the process 1000 determines that the second frameis an intra-BSS. The process 1000 then ends.

At S1016, the process 1000 determines whether an address of the secondframe is the same as the stored address. In an embodiment, the addressof the second frame is a receive address (RA) indicating an intendedreceiver of the second frame.

At S1016, when the address of the second frame is the same as the storedaddress, the process 1000 proceeds to S1018; otherwise the process 1000proceeds to S1020.

At S1018, the process 1000 determines that the second frame is anintra-BSS frame. In an embodiment, at S1018 the process 1000 updates theintra-BSS NAV using duration information included in the second frame.The process 1000 then ends.

At S1020, the process 1000 determines that the second frame is aninter-BSS frame. In an embodiment, at S1020 the process 1000 updates theinter-BSS NAV using duration information included in the second frame.The process 1000 then ends.

In an embodiment, a station determines that a frame received by thestation is an intra-BSS frame when one or more of the followingconditions is true:

-   -   An RXVECTOR parameter BSS_COLOR of a received PPDU carrying the        frame is the same as a BSS color announced by the AP to which        the station is associated,    -   The RA field, TA field, or BSSID field of the received frame        with the Individual/Group bit forced to the value 0 is the same        as the BSSID of AP to which the station is associated,    -   The AP to which the station is associated is a member of a        Multiple BSSID Set with two or more members and the RA field, TA        field, or BSSID field of the received frame with the        Individual/Group bit forced to the value 0 is same as the BSSID        of any member of the Multiple BSSID Set,    -   The RXVECTOR parameter PARTIAL_AID in a received VHT PPDU with        the RXVECTOR parameter GROUP_ID equal to 0 is the same as the        BSSID[39:47] of the AP to which the station is associated,    -   The value of RXVECTOR parameter PARTIAL_AID [8−N+1:8] in the        received VHT PPDU with the RXVECTOR parameter GROUP_ID equal to        63 is the same as the Partial BSS Color announced by the AP to        which the station is associated when the value (N) of the        Partial BSS Color Length field in the most recently received HE        Operation element is not equal to 0, or    -   The frame is a control (response) frame that does not have TA        field, and the RA address matches the saved TXOP holder address        for the BSS in which it is associated.

In an embodiment, the RXVECTOR parameter BSS_COLOR of the received PPDUis determined according to a BSS Color indication in an HE-SIG-A fieldof that PPDU.

In an embodiment, a station determines that a frame received by thestation is an intra-BSS frame when the frame is a control (response)frame that does not have a Transmission Address (TA) field, and aReceiver Address (RA) value of the frame matches a saved TXOP holderaddress for the BSS in which the station is associated.

In an embodiment, a station shall save a MAC address from the Address 2field of a frame that initiates a frame exchange sequence as a TXOPholder address for the BSS in which the station is associated when theframe is not a CTS frame. The station shall save an Address 1 field of aframe that initiates a frame exchange sequence as a TXOP holder addressfor the BSS in which the station is associated when the frame is a CTSframe. The station shall save a nonbandwidth signaling TA value obtainedfrom the Address 2 field of a frame that initiates a frame exchangesequence as a TXOP holder address for the BSS in which the frame isassociated when the frame is a Control frame and the station is a VHTstation or an HE station.

In an embodiment, when a station receives a first frame not targeted tothe station, the first frame is considered as an intra-BSS frame whenthe first frame is a control (response) frame that does not have a TAfield, and the RA address matches a saved TXOP holder address for theBSS in which it is associated.

In an embodiment, a station shall clear a saved TXOP holder address whenan inter-BSS NAV of the station is reset, an Intra-BSS NAV of thestation is reset, the inter-BSS NAV counts down to 0, or the Intra-BSSNAV counts down to 0.

FIG. 11 illustrates a process 1100 for determining whether a frame is anintra-BSS or inter-BSS frame, according to another embodiment. Theprocess 1100 is similar to the process 1000 of FIG. 10, and elements ofprocess 1100 perform similar function to similarly-numbers elements ofthe process 1000. For example, S1102 performs the same function asS1002, S1104 performs the same function as S1004, and so on.

The process 1100 differs from the process 1000 in that S1122 replacesS1008, S1124 and S1126 replace S1016, and S1128 replaces S1018. Thesenew elements are described below.

At S1122, the process 1100 stores an address of the first frame as astored address and in addition (compared to S1008 of FIG. 10) storesTXOP Duration information included in the first frame. In an embodiment,the address of the first frame is a transmission address correspondingto the first station.

At S1124, the process 1100 determines whether an address of the secondframe is the same as the stored address. In an embodiment, the addressof the second frame is a receiver address (RA) indicating an intendedreceiver of the second frame.

At S1124, when the address of the second frame is the same as the storedaddress, the process 1100 proceeds to S1126; otherwise the process 1100proceeds to S1120.

At S1126, the process 1100 compares TXOP duration information includedin the second frame to the TXOP duration information stored at S1122.When an end of the TXOP indicated by the TXOP duration informationincluded in the second frame matches an end of the TXOP indicated by theTXOP duration information stored at S1122, the process 1100 proceeds toS1128; otherwise the process 1100 proceeds to S1120.

At S1128, the process 1100 determines that the second frame is anintra-BSS frame and updates an intra-BSS NAV using the TXOP durationinformation included in the second frame. The process 1100 then ends.

In an embodiment, the MAC address of the TXOP holder could be an RA ofthe first frame. In an embodiment, xIFS could be a SIFS or a durationfor several frame exchanges. In an embodiment, the first frame could bean RTS frame or data frame. In an embodiment, the second frame could bea CTS or ACK frame with a legacy format. In an embodiment, the secondstation could be an AP and the first station could be a non-AP station.

FIG. 12A shows a frame exchange according to an embodiment. The frameexchange occurs between an AP and a first station STA1 and is observedby a second station STA2 that does not participate in the frameexchange. All of the AP, the first station STA1, and the second stationSTA2 are associated with a BSS having a BSS Identifier BSSID.

The first station STA1 holds a TXOP and transmits an RTS frame 1202 tothe AP. The second station STA2 also receives the RTS frame 1202. Thesecond station STA2, using the process 1000 of FIG. 10, determines thatthe RTS frame 1202 is an intra-BSS frame and as a result sets a STA2Saved TA Address 1220 to the TA value of the RTS frame 1202 and sets aSTA2 intra-BSS NAV 1216 using a duration signaled by the RTS frame 1202.

In response to the RTS frame 1202, the AP transmits a CTS frame 1204 tothe first station STA1. The second station STA2 also receives the CTSframe 1204. The second station STA2, using the process 1000, determinesthat the CTS frame 1204 does not contain valid BSS information andtherefore compares an RA address of the CTS frame 1204 to the STA2 SavedTA Address 1220. Because the RA address of the CTS frame 1204 matchesthe STA2 Saved TA Address 1220, the second station STA2, using theprocess 1000, determines that the CTS frame 1204 is an intra-BSS frame,updates the STA2 intra-BSS NAV 1216 using a duration signaled by the CTSframe 1204, and does not update a STA2 inter-BSS NAV.

In response to the CTS frame 1204, the first station STA1 transmits adata frame 1206 to the AP. The second station STA2 also receives thedata frame 1206. The second station STA2, using the process 1000,determines that the data frame 1206 in an intra-BSS frame and as aresult sets a STA2 Saved TA Address 1220 to the TA value of the dataframe 1206 and updates the STA2 intra-BSS NAV 1216 using a durationsignaled by the data frame 1206 when a value of the duration is largerthan the current STA2 intra-BSS NAV.

In response to the data frame 1206, the AP transmits an ACK or BA frame1210 to the first station STA1. The second station STA2 also receivesthe ACK or BA frame 1210. The second station STA2, using the process1000, determines that the ACK frame 1210 does not contain valid BSSinformation and therefore compares an RA address of the ACK frame 1210to the STA2 Saved TA Address 1220. Because the RA address of the ACKframe 1210 matches the STA2 Saved TA Address 1220, the second stationSTA2, using the process 1000, determines that the ACK frame 1210 is anintra-BSS frame, updates the STA2 intra-BSS NAV 1216 using a durationsignaled by the ACK frame 1210, and does not update the STA2 inter-BSSNAV.

After receiving the ACK or BA frame 1210, the first station STA1transmits a CF-End frame 1212 signaling an end of the TXOP. The secondstation STA2 also receives the CF-End frame 1212. In response toreceiving the CF-End frame 1212, the second station STA2 resets the STA2intra-BSS NAV 1216 and clears the STA2 Saved TA Address 1220.

FIG. 12B shows a frame exchange according to an embodiment. The frameexchange occurs between an AP and a first station STA1 and is observedby a second station STA2 that does not participate in the frameexchange. All of the AP, the first station STA1, and the second stationSTA2 are associated with a BSS having a BSS Identifier BSSID.

The frame exchange of FIG. 12B differs from the frame exchange of FIG.12A in that the second station STA2 does not receive the CTS frame 1204or the data frame 1206.

The first station STA1 holds a TXOP and transmits an RTS frame 1202 tothe AP. The second station STA2 also receives the RTS frame 1202. Thesecond station STA2, using the process 1000 of FIG. 10, determines thatthe RTS frame 1202 in an intra-BSS frame and as a result sets a STA2Saved TA Address 1220 to the TA value of the RTS frame 1202 and sets aSTA2 intra-BSS NAV 1216 using a duration signaled by the RTS frame 1202.

In response to the RTS frame 1202, the AP transmits a CTS frame 1204 tothe first station STA1. The second station STA2 does not receives theCTS frame 1204, as indicated by the “X” on the CTS frame 1204 in FIG.12B.

In response to the CTS frame 1204, the first station STA1 transmits adata frame 1206 to the AP. The second station STA2 does not receives thedata frame 1206, as indicated by the “X” on the data frame 1206 in FIG.12B.

In response to the data frame 1206, the AP transmits an ACK or BA frame1210 to the first station STA1. The second station STA2 also receivesthe ACK or BA frame 1210. The second station STA2, using the process1000, determines that the ACK frame 1210 does not contain valid BSSinformation and therefore compares an RA address of the ACK frame 1210to the STA2 Saved TA Address 1220. Because the RA address of the ACKframe 1210 matches the STA2 Saved TA Address 1220, the second stationSTA2, using the process 1000, determines that the ACK frame 1210 is anintra-BSS frame, updates the STA2 intra-BSS NAV 1216 using a durationsignaled by the ACK frame 1210, and does not update a STA2 inter-BSSNAV.

After receiving the ACK or BA frame 1210, the first station STA1transmits a CF-End frame 1212 signaling an end of the TXOP. The secondstation STA2 also receives the CF-End frame 1212. In response toreceiving the CF-End frame 1212, the second station STA2 resets the STA2intra-BSS NAV 1216 and clears the STA2 Saved TA Address 1220.

FIG. 13 illustrates a process 1300 for determining whether a frame is anintra-BSS or inter-BSS frame, according to another embodiment. Theprocess 1300 uses TXOP duration information to retroactively determinewhether a frame was an inter-BSS or intra-BSS frame.

At S1302, the process 1300 receives, over a wireless medium, a firstframe (frame 1) from a first station. In an embodiment, the first frameis a CTS frame or an ACK frame. In an embodiment, the first frame is nottargeted to the station performing the process 1300.

In an embodiment, the first station is a non-AP station.

At S1304, the process 1300 determines whether the first frame includesvalid BSS information. In an embodiment, valid BSS information includesColor information corresponding to a color of a BSS, an address of adevice that can be used to determine whether the device is associatedwith the BSS (such as a MAC address), or both.

At S1304, when the process 1300 determines that the first frame doesinclude valid BSS information, the process 1300 proceeds to S1322; andwhen the process 1300 determines that the first frame does not includevalid BSS information, the process proceeds to S1306.

At S1306, the process 1300 determines that the first frame is from anunclassified-BSS frame, deferring the determinations of whether thefirst frame is an inter-BSS or intra-BSS frame; the station performingthe process 1300 enters a deferred-NAV state; and the process 1300stores TXOP duration information that was indicated in the first frame.

In an embodiment, when the station performing the process 1300 is in thedeferred-NAV state, the station performing the process 1300 is notpermitted to perform a transmission to a wireless medium. In anembodiment, when the station performing the process 1300 is in thedeferred-NAV state, a back-off countdown procedure is postponed evenwhen the wireless medium seems to be idle.

At S1308, the process 1300 detects whether a second frame (frame 2) hasbeen transmitted on the wireless medium within a Short Inter-Frame Spaceof an end of the reception of the first frame. When the second frame hasbeen transmitted within the Short Inter-Frame Space of the end of thereception of the first frame, the process 1300 proceeds to S1310;otherwise, the process 1300 proceeds to S1318.

At S1310, the process 1300 receives the second frame over the wirelessmedium. In an embodiment, the second frame is not targeted to thestation performing the process 1300.

At S1312, the process 1300 determines whether the second frame includesvalid BSS information. When the second frame includes valid BSSinformation, the process 1300 proceeds to S1314; otherwise, the process1300 proceeds to S1318.

At S1314, the process 1300 determines, using the BSS information of thesecond frame, whether the station that transmitted the second frame isin myBSS of the station performing the process 1300. When the process1300 determines that the station that transmitted the second frame is inthe myBSS, the process 1300 proceeds to S1316; otherwise, the process1300 proceeds to S1318.

At S1316, the process 1300 compares TXOP duration information indicatedin the second frame to the TXOP duration information stored at S1306.When an end of the TXOP indicated by the TXOP duration informationindicated in the second frame matches an end of the TXOP indicated bythe TXOP duration information stored at S1306, the process 1300 proceedsto S1320; otherwise the process 1300 proceeds to S1318.

At S1318, the process 1300 determines that the first frame was aninter-BSS frame, updates an inter-BSS NAV using the stored TXOP durationinformation, and then ends.

At S1320, the process 1300 determines that the first frame was anintra-BSS frame, updates an intra-BSS NAV using the stored TXOP durationinformation, and then ends.

At S1322, the process 1000 determines whether station that transmittedthe first frame is in myBSS using the BSS information of the firstframe. When the station that transmitted the first frame is determinedto be in myBSS, the process 1300 determines that the first frame is anintra-BSS frame and updates, using duration information indicated in thefirst or second frame, an intra-BSS NAV. When the station thattransmitted the first frame is not determined to be in myBSS, theprocess 1300 determines that the first frame is an inter-BSS frame andupdates, using the duration information indicated in the first frame, aninter-BSS NAV. The process 1300 then ends.

The process 1300 operates under the assumption that a remaining TXOPduration in a PHY header or MAC header has been set to match the end ofa TXOP duration of an RTS frame that occurred at the beginning of frameexchange because there is no reason to update the value in the durationfield when inside of an initiated TXOP.

FIG. 14 illustrates a process 1400 for determining whether a frame is anintra-BSS or inter-BSS frame, according to another embodiment. Theprocess 1400 uses TA and RA information to retroactively determinewhether a frame is an inter-BSS or intra-BSS frame.

Features of process 1400 of FIG. 14 are similar to similarly-namedfeatures of process 1300 of FIG. 13. For example, S1402 of process 1400is similar to S1302 of process 1300, S1404 of process 1400 is similar toS1304 of process 1300, and so on. Process 1400 differs from process 1300in that S1430 of process 1400 replaces S1306 of process 1300 and S1432of process 1400 replaces S1316 of process 1300.

At S1430, the process 1400 determines that the first frame is from anunclassified-BSS frame, deferring the determinations of whether thefirst frame is an inter-BSS or intra-BSS frame; the station performingthe process 1400 enters a deferred-NAV state; and the process 1400stores TXOP duration information that was included in the first frame.In addition, at S1430 the process 1400 stores an RA of the first frame.

At S1432, the process 1400 compares TA included in the second frame tothe RA stored at S1430. When TA included in the second frame is the sameas the RA stored at S1430, the process 1400 proceeds to S1420; otherwisethe process 1400 proceeds to S1418.

In an embodiment, the first frame is a CTS frame. In an embodiment, thesecond frame is a data frame.

In an embodiment, the first frame is transmitted by a non-AP station. Inan embodiment, the second frame is transmitted by an AP.

FIG. 15 illustrates a frame exchange in which a station not involved inthe exchange does not receive a first frame of the frame exchange,according to another embodiment. The frame exchange occurs on a wirelessmedium between an AP and a first station STA1 and is observed by asecond station STA2 that does not participate in the frame exchange. Allof the AP and the first and second stations STA1 and STA2 are associatedwith a same BSS having a BSS Identifier BSSID.

The first station STA1 holds a TXOP and transmits an RTS frame 1502 tothe AP. The second station STA2 does not receive the RTS frame 1502, asindicated by the “X” on the RTS frame 1502 in FIG. 15.

In response to the RTS frame 1502, the AP transmits, over the wirelessmedium, a CTS frame 1504 to the first station STA1. The first stationSTA1 receives the CTS frame 1504.

The second station STA2 also receives the CTS frame 1504. When thesecond station STA2 is using the process 1400, the second station STA2also stores an RA included in the CTS frame 1504.

The second station STA2 also enters a deferred-NAV state, wherein thesecond station STA2 will not attempt any transmissions on the wirelessmedium.

In response to the CTS frame 1504, the first station STA1 transmits adata frame 1506 to the AP. The second station STA2 also receives thedata frame 1506. The second station STA2, using the process 1300 or theprocess 1400, determines that the data frame 1506 in an intra-BSS frame.

When the second station STA2 uses the process 1300, the second stationSTA2 determines whether the CTS frame 1504 was an intra-BSS frame or aninter-BSS frame by comparing the stored TXOP duration information fromthe CTS frame 1504 to TXOP duration information included in the dataframe 1506. When the second station STA2 uses the process 1400, thesecond station STA2 determines whether the CTS frame 1504 was anintra-BSS frame or an inter-BSS frame by comparing the stored RA fromthe CTS frame 1504 to TA in the data frame 1506.

When the second station STA2 determines that the CTS frame 1504 is theintra-BSS frame, the second station STA2 exits the deferred-NAV stateand updates an Intra-BSS NAV of the second station STA2 using the storedTXOP duration information from the CTS frame 1504 or TXOP durationinformation included in the data frame 1506. When the second stationSTA2 determines that the CTS frame 1504 is the inter-BSS frame, thesecond station STA2 exits the deferred-NAV state and updates anInter-BSS NAV of the second station STA2 using the stored TXOP durationinformation from the CTS frame 1504.

Embodiments can prevent a performance loss that may occur when anintra-BSS frame is not identified as an intra-BSS frame.

The solutions provided herein have been described with reference to awireless LAN system; however, it should be understood that thesesolutions are also applicable to other network environments, such ascellular telecommunication networks, wired networks, etc.

The above explanation and figures are applied to an HE station, an HEframe, an HE PPDU, an HE-SIG field and the like of the IEEE 802.11axamendment, but they can also applied to a receiver, a frame, PPDU, a SIGfield, and the like of another future amendment of IEEE 802.11.

Embodiments of the present disclosure include electronic devicesconfigured to perform one or more of the operations described herein.However, embodiments are not limited thereto.

Embodiments of the present disclosure may further include systemsconfigured to operate using the processes described herein. The systemsmay include basic service sets (BSSs) such as the BSSs 100 of FIG. 1,but embodiments are not limited thereto.

Embodiments of the present disclosure may be implemented in the form ofprogram instructions executable through various computer means, such asa processor or microcontroller, and recorded in a non-transitorycomputer-readable medium. The non-transitory computer-readable mediummay include one or more of program instructions, data files, datastructures, and the like. The program instructions may be adapted toexecute the processes and to generate and decode the frames describedherein when executed on a device such as the wireless devices shown inFIG. 1.

In an embodiment, the non-transitory computer-readable medium mayinclude a read only memory (ROM), a random access memory (RAM), or aflash memory. In an embodiment, the non-transitory computer-readablemedium may include a magnetic, optical, or magneto-optical disc such asa hard disk drive, a floppy disc, a CD-ROM, and the like.

In some cases, an embodiment of the invention may be an apparatus (e.g.,an AP station, a non-AP station, or another network or computing device)that includes one or more hardware and software logic structure forperforming one or more of the operations described herein. For example,as described above, the apparatus may include a memory unit, whichstores instructions that may be executed by a hardware processorinstalled in the apparatus. The apparatus may also include one or moreother hardware or software elements, including a network interface, adisplay device, etc.

While this invention has been described in connection with what ispresently considered to be practical embodiments, embodiments are notlimited to the disclosed embodiments, but, on the contrary, may includevarious modifications and equivalent arrangements included within thespirit and scope of the appended claims. The order of operationsdescribed in a process is illustrative and some operations may bere-ordered. Further, two or more embodiments may be combined.

What is claimed is:
 1. A method performed by a first wireless device fordetermining a Basic Service Set (BSS) associated with a wirelesstransmitter, the method comprising: receiving, by the first wirelessdevice, a first frame; determining an address of the first frame;receiving, by the first wireless device, a second frame; determining, bythe first wireless device, an address of the second frame; determining,using the address of the first frame and the address of the secondframe, whether the second frame is an inter-BSS frame; and setting aninter-BSS Network Allocation Vector (NAV) in response to determiningthat the second frame is an inter-BSS frame, wherein the first wirelessdevice comprises the inter-BSS NAV and an intra-BSS NAV different fromthe inter-BSS NAV.
 2. The method of claim 1, further comprising:determining, using the address of the first frame and the address of thesecond frame, whether the second frame is an intra-BSS frame.
 3. Themethod of claim 2, further comprising: comparing the address of thesecond frame with the address of the first frame; determining that thesecond frame is the intra-BSS frame when the address of the first framematches the address of the second frame; and determining that the secondframe is the inter-BSS frame when the address of the first frame failsto match with the address of the second frame.
 4. The method of claim 3,wherein the address of the second frame is a receive address (RA) andthe address of the first frame is a transmit address (TA).
 5. The methodof claim 3, further comprising: setting the intra-BSS NAV in response todetermining that the second frame is an intra-BSS frame.
 6. The methodof claim 1, wherein the first frame is not targeted to the firstwireless device.
 7. The method of claim 1, wherein the second frame isnot targeted to the first wireless device.
 8. The method of claim 1,further comprising: determining whether the first frame is an intra-BSSframe, wherein determining the address of the first frame comprises:storing the address of the first frame when the first frame isdetermined to be an intra-BSS frame.
 9. The method of claim 1, whereinthe address of the first frame is a transmitter address of a secondwireless device transmitting the first frame.
 10. The method of claim 1,wherein the address of the first frame is an address of a holder of aTransmission Opportunity (TXOP) in which the first frame is transmitted.11. The method of claim 1, wherein receiving the second frame comprisesreceiving the second frame within a Short Intra-Frame Space (SIFS) of anend of receiving the first frame.
 12. The method of claim 1, whereinreceiving the second frame comprises receiving the second frame within aduration of a Transmission Opportunity (TXOP).
 13. The method of claim1, further comprising: determining whether the second frame includesvalid BSS information, the BSS information providing an indication of aBSS that the device transmitting the first frame is associated with,wherein determining, using the address of the first frame, the propertyof the second frame is performed in response to the second frame beingdetermined to not include the valid BSS information.
 14. The method ofclaim 1, wherein the first frame is a request-to-send (RTS) frame andthe second frame is a clear-to-send (CTS) frame or the first frame is adata frame and the second frame is an acknowledgement frame.
 15. Awireless device, comprising: a receiver circuit; an inter-Basic ServiceSet (BSS) Network Allocation Vector (NAV); and an intra-BSS NAVdifferent from the inter-BSS NAV, wherein the wireless device is todetermine a BSS associated with a wireless transmitter, whereindetermining the BSS associated with the wireless transmitter comprises:receiving, using the receiver circuit, a first frame; determining anaddress of the first frame; receiving, using the receiver circuit, asecond frame; determining an address of the second frame; determining,using the address of the first frame and the address of the secondframe, whether the second frame is an inter-BSS frame; and setting theinter-BSS NAV in response to determining that the second frame is theinter-BSS frame.
 16. The wireless device of claim 15, whereindetermining whether the second frame is an inter-BSS frame comprises:comparing the address of the second frame with the address of the firstframe, wherein the second frame is determined to be an intra-BSS framewhen the address of the first frame matches the address of the secondframe and the second frame is determined to be an inter-BSS frame whenthe address of the first frame fails to match with the address of thesecond frame.
 17. The method of claim 16, wherein the address of thesecond frame is a receive address (RA) and the address of the firstframe is a transmit address (TA).
 18. The wireless device of claim 15,wherein the first frame is not targeted to the wireless device and thesecond frame is not targeted to the wireless device.
 19. The wirelessdevice of claim 15, wherein determining the BSS associated with thewireless transmitter further comprises: determining whether the firstframe is an intra-BSS frame, and storing the address of the first framein response to determining that the first frame the intra-BSS frame.